The present invention relates to a spot welding apparatus for spot-welding overlapped articles or workpieces to be welded, at least one of which has a coating on its outer surface. The spot welding apparatus according to the present invention comprises a welding power source for supplying a low-voltage, large-current welding energy, a first cable drawn from one pole of the welding power source, a first welding electrode tip connected to an end of said first cable, second and third cables connected to the other pole of the welding power source, a second welding electrode tip connected to an end of said third cable, and a contact member provided at an end of said second cable, said contact member contact-connecting to metal-exposed surfaces at portions of the articles to be welded which portions are spaced apart from a spot welding area of the overlapped articles to be welded.